Data Acquisition Toolbox

Creating a Digital I/O Object

You create a digital I/O (DIO) object with the digitalio function. digitalio accepts the adaptor name and the hardware device ID as input arguments. For parallel ports, the device ID is the port label (LPT1, LPT2, or LPT3). For data acquisition boards, the device ID refers to the number associated with the board when it is installed. Note that some vendors refer to the device ID as the device number or the board number. Use the daqhwinfo function to determine the available adaptors and device IDs.

Each DIO object is associated with one parallel port or one subsystem. For example, to create a DIO object associated with a National Instruments board:

• dio = digitalio('nidaq',1);
  

The digital I/O object dio now exists in the MATLAB workspace. You can display the class of dio with the whos command.

• whos dio
    Name      Size         Bytes  Class
  
    dio       1x1           1308  digitalio object
  
  Grand total is 40 elements using 1308 bytes
  

Once the object is created, the properties listed below are automatically assigned values. These general purpose properties provide descriptive information about the object based on its class type and adaptor.

Table 7-1: Descriptive Digital I/O Properties 

Property Name	Description
Name	Specify a descriptive name for the device object.
Type	Indicate the device object type.

You can display the values of these properties for dio with the get function.

• get(dio,{'Name','Type'})
  ans = 
      'nidaq1-DIO'    'Digital IO'
  

Digital Input/Output

The Parallel Port